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[PATCH 2/2] Add VDSO version of sched_getcpu on powerpc
- From: Anton Blanchard <anton at samba dot org>
- To: libc-alpha at sourceware dot org
- Date: Mon, 9 Jul 2012 11:28:54 +1000
- Subject: [PATCH 2/2] Add VDSO version of sched_getcpu on powerpc
- References: <20120709112735.22c2e72b@kryten>
The kernel patch has been submitted and is in the review process.
Results on a POWER7 show the speedup of a sched_getcpu call:
baseline: 538 cycles
vdso: 30 cycles
2012-07-09 Anton Blanchard <anton@samba.org>
* sysdeps/unix/sysv/linux/powerpc/sched_getcpu.c: New file.
* sysdeps/unix/sysv/linux/powerpc/Versions: Add __vdso_getcpu
* sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h: Likewise.
* sysdeps/unix/sysv/linux/powerpc/init-first.c: Likewise.
---
sysdeps/unix/sysv/linux/powerpc/sched_getcpu.c | 30 +++++++++++++++++++++++
sysdeps/unix/sysv/linux/powerpc/Versions | 1
sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h | 2 +
sysdeps/unix/sysv/linux/powerpc/init-first.c | 3 ++
4 files changed, 36 insertions(+)
Index: glibc/sysdeps/unix/sysv/linux/powerpc/sched_getcpu.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ glibc/sysdeps/unix/sysv/linux/powerpc/sched_getcpu.c 2012-06-25 09:44:20.067041483 +1000
@@ -0,0 +1,30 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sched.h>
+#include <sysdep.h>
+#include <bits/libc-vdso.h>
+
+
+int
+sched_getcpu (void)
+{
+ unsigned int cpu;
+ int r = INLINE_VSYSCALL (getcpu, 3, &cpu, NULL, NULL);
+
+ return r == -1 ? r : cpu;
+}
Index: glibc/sysdeps/unix/sysv/linux/powerpc/Versions
===================================================================
--- glibc.orig/sysdeps/unix/sysv/linux/powerpc/Versions 2012-06-25 09:42:38.000000000 +1000
+++ glibc/sysdeps/unix/sysv/linux/powerpc/Versions 2012-06-25 09:44:20.067041483 +1000
@@ -3,5 +3,6 @@ libc {
__vdso_get_tbfreq;
__vdso_clock_gettime;
__vdso_clock_getres;
+ __vdso_getcpu;
}
}
Index: glibc/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h
===================================================================
--- glibc.orig/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h 2012-06-25 09:42:38.000000000 +1000
+++ glibc/sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h 2012-06-25 09:44:20.067041483 +1000
@@ -30,6 +30,8 @@ extern void *__vdso_clock_getres;
extern void *__vdso_get_tbfreq;
+extern void *__vdso_getcpu;
+
#endif
#endif /* _LIBC_VDSO_H */
Index: glibc/sysdeps/unix/sysv/linux/powerpc/init-first.c
===================================================================
--- glibc.orig/sysdeps/unix/sysv/linux/powerpc/init-first.c 2012-06-25 09:43:43.000000000 +1000
+++ glibc/sysdeps/unix/sysv/linux/powerpc/init-first.c 2012-06-25 09:44:20.067041483 +1000
@@ -26,6 +26,7 @@ void *__vdso_gettimeofday attribute_hidd
void *__vdso_clock_gettime;
void *__vdso_clock_getres;
void *__vdso_get_tbfreq;
+void *__vdso_getcpu;
static inline void
@@ -40,6 +41,8 @@ _libc_vdso_platform_setup (void)
__vdso_clock_getres = _dl_vdso_vsym ("__kernel_clock_getres", &linux2615);
__vdso_get_tbfreq = _dl_vdso_vsym ("__kernel_get_tbfreq", &linux2615);
+
+ __vdso_getcpu = _dl_vdso_vsym ("__kernel_getcpu", &linux2615);
}
# define VDSO_SETUP _libc_vdso_platform_setup